Method of moulding and applying marks on a surface

ABSTRACT

A method by which an elastomer is applied to a model (1) with relief marks to be reproduced. The purpose of the elastomer once set is to form a mold membrane (14) and incorporate within its own material the shape of the marks on the model. The mold membrane is then separated from the model and filled with a setting material, and the mold membrane is applied to a support in order to transfer the marks after preliminary pasting.

FIELD OF THE INVENTION

The present invention relates to the field of fixing elements tosupports and relates more particularly to a process for molding andapplying three-dimensional indications to a surface such as a timepiecedial which acts as a support.

BACKGROUND OF THE INVENTION

Processes for fixing elements to supports, such as the processes oftransfer printing by means of an etched block and a pad, have been knownfor a long time and give very good results when the indications to bereproduced are flat and thin, but these processes becomes [sic] moredifficult to use when it is desired to obtain more substantialthicknesses. Other techniques such as insertion or adhesive coating havehitherto enabled three-dimensional indications to be fixed by placingthem individually.

Other processes exist in which the indications to be affixed, forexample to a dial, are produced by cutting a sheet consisting of acompound possibly containing luminescent material, the indicationsobtained having a flat shape. However, this process, on the one hand,does not allow the production of indications of elaborate shape and, onthe other hand, presupposes a manipulation carried out by an operator inorder to place them on the support.

SUMMARY OF THE INVENTION

The present invention aims to overcome all these drawbacks and moreparticularly to allow the creation of indications of any shape and/orthickness, while eliminating the manipulation of the indications by anoperator during the procedure of laying them on the support. The processfor transferring indications to a surface according to the invention ischaracterized in that an elastomer is applied to a pattern having atleast one indication in relief to be reproduced, this elastomer, afterhaving cured, being intended to form a membrane-mold and to reproduce innegative the indication in relief on the pattern, in that themembrane-mold is separated from the pattern, in that the membrane-moldis filled with a compound capable of curing and in that themembrane-mold containing the indication filled with the cured compound,or the compound in the process of curing, is applied to a support so asto transfer the indication after having precoated the place or thevisible surface of the indication with adhesive.

The invention also relates to a tool for implementing this process,characterized in that it comprises a retaining piece having at least oneorifice, the piece having at least one indexing notch or perforation,molding pieces gripping the retaining piece and the pattern forproducing the membrane-mold by molding.

The subject of the invention is also the support obtained byimplementing the process.

BRIEF DESCRIPTION OF THE DRAWINGS

The appended drawing shows, by way of non-limiting examples, anembodiment and variants of the process according to the invention.

FIG. 1 shows a top view of an initial pattern for a dial, comprisingindications in relief which it is desired to reproduce and affix to asurface, the initial pattern being in the form of a disk with anindexing notch.

FIG. 2 is a cross section on the line II--II of the pattern in FIG. 1.

FIG. 3 represents a ring having the same external dimension as thepattern in FIG. 1, also with an indexing notch.

FIG. 4 is a cross section on the line IV--IV of the ring in FIG. 3, onan enlarged scale, in which may be seen a rectangular channel on theoutside and a dovetail machined cut on the inside.

FIG. 5 shows a device for producing a membrane-mold intended toreproduce the indications in relief.

FIG. 6 details the connection between the membrane-mold and the ring.

FIG. 7 shows one way of manually filling the mold using a fillingnozzle.

FIG. 8 gives another alternative way of filling, by deposition andscraping of the upper surface of the mold with a blade.

FIG. 9 represents said membrane-mold filled with the molded compounds.

FIG. 10 represents a device used for transfer printing and coating thesurface intended to receive the molded compounds with adhesive, using aninverted block, a pad and a sliding support.

FIG. 11 shows the relative positioning of the surface precoated withadhesive and the membrane-mold containing the molded compounds beforethe operation of placing the compounds using a positioning tool.

FIG. 12 shows the contacting of the compounds with the surface using anapplication tool.

FIG. 13 illustrates the deformation of the membrane-mold, allowingtransfer of a molded compound, with application of a vacuum using atool.

FIG. 14 shows the transfer of a molded compound having a shape withconcave parts.

FIG. 15 represents a succession of membrane-molds injected over holesmade on a flexible support in the form of a tape.

FIG. 16 is a section through a membrane-mold of the support on the lineXVI--XVI in FIG. 15, and

FIG. 17 is a section through an injection device gripping the tape ofthe support in FIG. 15 and allowing the succession of membrane-molds tobe produced continuously.

DETAILED DESCRIPTION OF THE INVENTION

The pattern in FIG. 1 is a dial pattern for a timepiece havingthree-dimensional indications exhibiting a certain relief. The standarddial in FIG. 1 represents a definitive pattern which will serve toproduce the tooling devices and the molds used for the mass manufactureof timepieces to be reproduced. It comprises a disk 1 on which theindications 2-5 to be molded are produced either by machining or bybonding or welding to the surface. The pattern serves as a die for afirst operation of molding and positioning the indications on surfacesrepresenting the blank for the dials to be manufactured.

Although the pattern shown is a timepiece, it is obvious that theprocess which will be described below is not limited to this applicationand that it may be applied to the production of dials or any surfacebearing three-dimensional indications used in mechanical engineering,electronics, etc.

The initial pattern shown in FIG. 1 is in the form of a disk 1, thesurface of which has various indications 2, 3, 4, 5 which may havevaried three-dimensional shapes. This pattern will be used for producingone or more molds which will make it possible to manufacture and containthe indications in accordance with the original. The indicationscontained in the molds may then be fixed to a support in a singleoperation. The edge of the disk 1 furthermore has an indexing notch 6.

With the pattern in FIGS. 1 and 2, the first operation carried out isthe manufacture of at least one membrane-mold. In order to support thismembrane-mold, a ring 7, shown in FIGS. 3 and 4 and provided with anindexing notch 8 corresponding to the notch 6 in the disk 1, isadvantageously used. The ring 7 is machined with a dovetail internalprofile 9 so as to be able to retain the membrane.

The disk 1 and the ring 7 are placed freely, without any clearance, asshown in FIG. 5, inside a molding device or die 11, the disk 1 and thering 7 being placed in superposition, making the indexing notch 6 in thedisk 1 coincide with the indexing notch 8 in the ring 7.

Placed on this assembly is a cover 12 having the general shape of afunnel opening onto a central orifice 13 intended for passage of asilicone compound 15 poured onto the assembly. Since the base of thecover is substantially planar, the excess silicone 15 in the funnel ofthe cover 12 can be recovered. The substance 15 employed in this case isa two-part silicone elastomer whose most important characteristics areits elasticity, its mechanical strength and chemical resistance, its lowshrinkage and excellent temperature withstand behavior. Other substanceswith similar properties may be used.

In this way, a membrane-mold 14 having an elastic character is obtained,this membrane-mold 14 being supported by ring 7, as shown in FIG. 6. Themembrane-mold 14 has hollow regions 16 formed, during molding, by thethree-dimensional indications 2 to 5. This operation may be repeatedseveral times so as to cast the desired number of membrane-molds 14intended for the production run.

The next step in the process corresponds to filling the membrane-moldshown in FIG. 6. There are several possibilities. In one preferredalternative, illustrated in FIG. 7, one may opt for a system of fillingusing a metering apparatus having a nozzle 17 for dispensing a fillingcompound 18, this system being either manual or controlled by anumerical-control machine, not shown. In another variant, the fillingmay be accomplished by pouring a suitable amount of filling compound 19(FIG. 8) and subsequently razing the surface using a doctor blade 20intended to remove the excess material. Another alternative would be tocarry out the operation by means of a vibrating action, not shown.

FIG. 9 shows a membrane-mold 14 held in the ring, the hollow regions 16being filled with the filling compounds 18 or 19.

The filling compound 18 or 19 is, in a preferred case, composed of atransparent lacquer with which has been premixed with a luminescent orpigmented powder which polymerizes in a few seconds under ultravioletradiation. Acrylic resins or other resins drying in air or in an ovenmay also be used. The luminescent powders may be based ontritium-treated zinc sulfite and sulfate, allowing the indications onthe dial to be seen at night.

Other alternative filling substances should be considered in order tovary the colors or to obtain other desired effects.

The molded compounds 18 or 19, depending on their nature, are cured byvarious processes: ultraviolet radiation, oven treatment, ambient air,etc. As mentioned above, one or more membrane-molds are necessary forthe production run, depending on the ratio between the time for themolded compounds to cure and the time for applying these compounds onthe dial.

The next phase, illustrated in FIG. 10, consists in applying the curedmolded compounds to the surface 21 intended to receive them. To do this,said surface or the indications must be precoated with adhesive, eithermanually using a metering device or using a metering dispenser mountedon a numerical-control machine or by a transfer printing system, whichprocess is well known in the manufacture of watch dials. In the lattercase, a metal block 22 is used which has the indications 23 to be bondedetched on its surface to a slightly smaller size. This etching operationcould be performed by covering the original block 22 with aphotosensitive film (photographic printing technique) and thereaftertreating the unmasked parts with acid. Once the block 22 has been fixedto its movable frame 24, it is coated with adhesive and, after scrapingwith a spatula, the impression is taken using a gelatin or silicone pad25. The adhesive is deposited on the surface 21 to be coated (dial orindication) using said pad 25. The movable frame 24, and likewise thepad 25, is controlled by a device, not shown, having, for example,translation sideways and limit stops allowing relative positioning ofthe surface 21 with respect to the block 22 (FIG. 10).

As illustrated in FIG. 11, the membrane-mold 14 is accurately placed, bymeans of an indexing device 26, on the surface 21 having spots ofadhesive 27, leaving a suitable heightwise clearance 28.

The membrane-mold 14 is pressed against the adhesive-coated surface ofthe support 21 using an application tool 29, shown diagrammatically inFIG. 12 and 13, and the molded indications 18, 19 are released via theedges of the membrane by creating, by means of the ducts 30a, a vacuumin the suction chambers 30 provided in the tool 29. Advantageously, thetool 29 may also be produced from the molding die in FIG. 1 according tothe following operations:

a) use of a membrane-mold 14 such as the one produced and described withregard to FIG. 6, the membrane-mold 14 being placed in the die shown inFIG. 5, after having been turned it upside down;

b) filling the hollow regions 16 of the membrane-mold 14 using anonelastic material capable of curing, for example polyurethane orpolyester resin, or else an epoxy;

c) the cured compounds are recovered on a doublesided rigidself-adhesive tape and then transferred by bonding, still using the dieshown in FIG. 5, to a support disk which will itself be used as theapplication tool 29 after having been pierced so as to render thesuction chambers 30 operational.

This manner of operating has the advantage of producing all the toolsprecisely, starting from the pattern in FIG. 1 and using the die in FIG.5. Thus, all the molding, positioning and transfer operations arecarried out with the same die, starting from the initial pattern in FIG.1.

The membrane-mold 14 is extracted by means of the suction chambers 30and the molded indications 18, 19 are applied at the desired point.Thereafter, the membrane-mold 14 is released from the application tool29 and may be filled again.

FIG. 14 shows an enlarged scale of a molded indication 32 which isparticularly high and also has a lateral recess 31 allowed by theprocess described up to now.

The process which has just been described has the following advantages:

the indications are no longer touched during the production of a piece,this being particularly advantageous when using radioactive indications;

the precision is uniform during molding and transfer, the indicationsbeing positioned once and for all during an initial adjustment and allthe operations being carried out using the membrane-mold and the die inFIG. 5;

compared to the processes of the prior art, there is a considerablesaving in time, given that the work may be carried out in massproduction using several membrane-molds, all produced with the sameinitial pattern.

In order to transfer indications continuously, the process describedwith regard to FIGS. 1 to 14 requires the production of 4 to 8membrane-molds according to FIGS. 3 to 6. Thus, the various stationsallowing membrane-mold filling, drying, adhesive coating and placing ofindications on a support, may be provided.

In the variant of the process described with regard to FIGS. 15 to 17,the membrane-molds 40 are produced continuously on a flexible supportwhich is in the form of a tape 41 having holes 42 over which saidmembrane-molds 40 will be injected. The support 41 has, between theholes 42, perforations 43 which will serve to position the tape 41during the various operations of producing the membrane-molds 40,filling said membrane-molds and placing the indications 44 (FIG. 16) ona support, not shown. In order to fasten the tape 41 to themembrane-molds 40 and avoid any relative displacement between the twocomponents (tape 41 and membrane-molds 40), anchoring perforations 45placed around the holes 42 are provided on the tape 41. Thus, duringproduction of the membrane-molds 40 by injection molding, as shown inFIG. 17, the material injected between two jaws 46 and 47 of the moldingdevice gripping the tape 41 will enter the perforations 45 and fasteneach membrane-mold to the tape 41. The molding device in FIG. 17 issimilar to that described with regard to FIG. 5, with its cover or top12 (FIG. 5) containing the initial pattern or disk 48 corresponding tothe pattern 1 in FIG. 1. The lower jaw 47 includes a central orifice 13intended for passage of the silicone compound which is injected andwhich, after having cured, is intended to form the membrane-molds 40.The jaws 46, 47 of the molding device in FIG. 17 are positioned using aguide punch 49 which enters the perforations 43 for positioning the tape41.

As described above with regard to FIGS. 4 to 6, the material used forproducing the membrane-molds is a two-part silicone injected cold intothe jaws 46, 47 of the preheated mold. Placed at the bottom of one ofthe jaws 46, 47 will be a disk, not shown, similar to that in FIG. 1having the indications to be impregnated in the membrane-mold. As avariant, the indications to be impregnated in the membrane-mold may beformed on the bottom of one of the jaws 46, 47. The support used is aflexible support in the form of a polyester or polycarbonate tape. Thetape 41 with its membrane-molds obtained by overmolding is, after themembrane-molds have cured, used for passing on to the phase of fillingthe indications, as shown in FIGS. 6 to 9, and then to the phase ofadhesive coating and of transferring the indications to a support. Thevariant which has just been described has the advantage whereby thevarious phases of overmolding the membrane-molds, filling theindications, adhesive coating and transferring said indications may becarried out separately or continuously. The tapes containing theindications may also be stored and the tapes may be used in a lost-moldprocess or be reused after the indications which they contained havebeen transferred.

The process which has just been described has the following advantages:

1. Control of the drying time during mold-membrane production andcontrol of the drying time during indication filling.

2. Manipulations by an operator, for example if the indications areradioactive, are avoided. Possibility of storing the tapes containing ornot containing the indications.

3. No wear--the tapes are simply thrown away after they have been usedone or more times. Guarantee of quality and precision.

4. The process may be completely automated and used continuously or inseparate phases (drying, filling, etc.).

Finally, the process which has just been described offers thepossibility, if desired, of placing inserts in the indications or ofproducing multilayer indications.

What is claimed is:
 1. A process for transferring indications to asurface, the process comprising the steps of:applying an elastomer to apattern having at least one indication in relief to be reproduced;curing the elastomer to form a membrane-mold thereby reproducing, innegatives, the at least one indication in the membrane-mold; separatingthe membrane-mold from the pattern; filling the membrane-mold with acompound capable of curing, the compound forming a reproduction of theat least one indication; coating at least one of the surface and thereproduction of the at least one indication with an adhesive; applyingthe membrane-mold containing the reproduction of the at least oneindication to the surface so as to transfer the reproduction of the atleast one indication to the surface.
 2. The process as claimed in claim1, wherein the membrane-mold is produced so that the thickness of itslayer may contain three-dimensional indications exhibiting aconsiderable relief.
 3. The process as claimed in claim 1, wherein anapplication tool is produced for transferring the indications havingparts in relief corresponding to the shape of the indications to betransferred and hollow parts surrounding the parts in relief, the partsin relief bearing on the membrane-mold at the place of the indicationsand the hollow parts being connected to orifices allowing a vacuum to becreated between the membrane-mold and the hollow parts in order to pressthe membrane-mold against said hollow parts and thus disengage theperiphery of the indications.
 4. The process as claimed in claim 1,wherein the elastomer of the membrane-mold is a two-part siliconeelastomer.
 5. The process as claimed in claim 1, further comprising thestep of positioning the membrane-mold above the surface prior totransferring the reproduction of the at least one indication from themembrane-mold to the surface.
 6. The process as claimed in claim 1,wherein several membrane-molds are produced, these being intended to beused continuously in the phases of membrane manufacture, filling andtransfer of the indications.
 7. The process as claimed in claim 6,wherein the membrane-mold is overmolded over an orifice provided in aretaining piece, the piece having indexing notches or perforations. 8.The process as claimed in claim 7, wherein the retaining piece is in theform of a plastic tape provided with a succession of orifices, amembrane-mold being overmolded over each orifice.
 9. A tool forproducing a membrane-mold containing a negative mold of indicationsformed on a pattern support, the tool comprising:a retaining piecehaving at least one orifice, the piece having at least one indexingnotch or perforation; a first molding piece gripping the retaining pieceand the pattern support; and a second molding piece disposed above thefirst molding piece and containing an elastomer, wherein the secondmolding piece delivers the elastomer to the pattern support and theorifice of the retaining piece thereby producing the membrane-moldcontaining the negative mold of the indications.
 10. The tool as claimedin claim 9, wherein the retaining piece is a ring (7) having a dovetailinternal profile (9) intended to retain the membrane-mold, the ringincluding an indexing notch (8) allowing it to be positioned relative tothe pattern or to the support.
 11. The tool as claimed in claim 9wherein the retaining piece is a tape (41) having a succession oforifices (42) over each of which a membrane-mold (40) is overmolded, thetape having indexing perforations (43).
 12. The tool as claimed in claim9, wherein the negative mold in the membrane-mold is filled with acompound thereby forming reproductions of the indications, the toolfurther comprising:a suction tool having parts in relief whichcorrespond to the shape and to the place of the reproduction indicationscontained in the membrane-mold, the parts in relief being surrounded bysuction chamber (30), the suction tool being placed on themembrane-mold.
 13. The tool as claimed in claim 12, wherein the suctiontool (29) is produced from the membrane-mold.
 14. A process fortransferring indications to a surface, the process comprising the stepsof:applying an elastomer to a pattern wherein the pattern has a set ofindications in relief to be reproduced; curing the elastomer to form amembrane-mold thereby reproducing, in negative, the indications in themembrane-mold; separating the membrane-mold from the pattern; fillingthe membrane-mold with a compound capable of curing, the compoundforming a reproduction of the indications; coating at least one of thesurface and the reproduction of the indications with an adhesive; afterthe coating, applying the membrane-mold containing the reproduction ofthe indications to the surface in an automated operation so as totransfer the reproduction of the indications to the surface.